Welder



6 Sheets-Sheet 1 INVENTUM Wwf 4 TTOQNEY WELDER Filed Jan. 22, 1942 G. J. FRlscHMANN ETAL March 5, 1946.

March 5, 1946. c. J. FRlscHMANN ETAL 255965002 wELDER I I Filed Jan. 22, 1942 e sheets-sheet 4 dol/"5 6 Byauv/ A TTOQNEY INVENToR/s March 5, 1946. G. J. FRlscHMANN ETAL 2,396,002

wELDER Filed Jan. 22, 1942 s sheets-sheet 5 ATTUPNEY Patented Mar. 5, l 19f16 `Wannen George J. Frischmann, Queens Village,'and Carl` F. Brunner, Wooiihaven,y N. Y., assignors to Metropolitan Engineering Company, Brooklyn. N. Y., a corporation of New York f Application January 22, 1942, Serial No. 427,730

The invention herein disclosed relates to a welder that is suitable for carrying out the welding process commonly known as electric resistance welding.y

Welds of the kind mentioned are eiected by) utilizing the electrical resistance of the metal pieces to bewelded to etlect the heating of the pieces, in the weld area. The pieces are first brought 4into contact and a heavy electric current is caused'to ow between, the pieces, a current of such magnitude that the pieces are heated in the weld area to a point where the metal becomes plastic. The pieces are then moved together under heavy pressure to cause the metal of each piece to flow into and become ingrained in the other. A machine for eil'ecting such welds should, i'orthe repeated production of satisfactory welds, be so arranged and constructed to effect an accurate relation between the pieces to be welded with a uniform pressure thereon so 'that the current density throughout the Aweld area may bev controlled to effect the proper rate of heating. In

addition the pressure exerted'on the pieces should be closely controlled in relation to the progress of `the welding operation.

An object of this invention is to provide a machine of this kind in which relatively movable electrode holders are accurately and definitely related in all positions of their relative movement. Another object of the invention is to provide a machine of this kind in which the pressureexerted on pieces being-welded may be accurately controlled and varied in relation to the progress of the welding operation. A further object of the invention is to provide a mach-ine of this kind suitable for automatic control during the welding operation. Another object oi' the invention is to' provide a machine of this kind having automatic controls.

The foregoing objects, and certain advantages inherent in this invention, are realized in the embodiment o1' the invention illustrated as an example in the accompanying drawings and described n elevation illustrating the control. rod and associated mechanism;

Fig. 5 which is a diagrammatic illustration 0l the hydraulic system: and

l5 oi' the pieces.

plied to the electrodes and the pieces therebe' Fig. 6 which is a wiring diagram of the electrical control circuits.

AIn general, the Welder illustrated in the drawings includes a frame that supports the operative mechanism and the transformer which supplies the welding current. 'I'here Mare two electrode holders or shoes which are relatively movable. To

these electrode shoes, suitable electrodes are secured, the electrodes being such that they engage one surface of each of the pieces to b`e Welded, ex-

cept in the weldarea. When the pieces to be welded are arranged in the Welder so as to be engaged by the electrodes, the lelectrode shoes are moved relatively to effect a pressure engagement The welding current is then. suptween are in the circuit. As the metal of the pieces becomes plastic from the heat generated by the passage of the weld Icurrent therethrough the 20. electrode shoes move closer Itogether and `additional pressure is exerted on the electrode shoes to cause the metal of each piece to flow into, become ingrained in and coalesce with the other. Movement ofthe electrode shoes towards each other is limited to determine the size of the welded e piece and the extent of ilow of the metal of the n pieces. vAs the weld is effected, thewelding current is cut ofi.' and the electrode shoes continue to move toward each other under increased pressure until further motion is prevented by the' size the welded piece.

The particular embodiment of the invention illustrated in the drawings include a base or frame I on which the' electrode shoes and the operating parts of the machine are mounted. This base'in- 40 cludes an extension 2.which serves to support a l transformer l from which the welding current is supplied to the electrodes. The hydraulic system Ythrough-which movement of the electrode shoe is effected and which includes a reservoir. pump and magnetically operated valves is built as aunit and placed behind the Welder: it is connected to the Welder by flexible, high pressure Neoprene l hose.

Mounted directly upon .the frame i is a bed plate I. This bed plate is provided with four shoulder bushings l, arranged at the corners of a square. The plate is bored to have openings aligned with the bushings. Mounted n the be'd plate and secured thereto, and electrically insulated. thereirnm there is'an electrode shoe l which i upper contact Il.

is within the square at the corners of which the shoulder bushings are located. The electrode f shoe receives an electrode 1, the lower electrode,

which is secured therein by a wedge 8. The electrode shoe also carries guide pins 9 which extend therefrom and which are electrically insulated from the electrode shoe. Held in place by these guide pins, there are size blocks Ill, one on either side of the electrode shoe. These size blocks are made of electrical insulating material and serve to limit the extent of movement of the electrodes towards each other.

Slidably mounted in each of the shoulder bushings 5 there is a guide post I I. At the upper end, there is secured to the guide posts a ram plate I2. This ram plate is securely fastened to the guide posts adjacent the upper end of the guide posts. The top plate carries an electrode shoe I3, insulated therefrom, in which is mounted the upper electrode I4, secured therein by a wedge I5.

y The lower electrode is connected to one side of -der bushings in the bed plate and into the base I. At their lower ends, the guide posts II are firmly secured to a bottom plate I8. Within base I a hydraulic cylinder I3 is mounted. This hydraulic cylinder extends from the bed plate 4 on which it is mounted within the base so that the axis thereof is aligned with the center of the bottom plate I8. Within the cylinder, there is a piston that is connected to a piston rod extending through the lower end of the cylinder I8 and connected to the bottom plate I8. By admitting fluid under pressure to the top of the cylinder, as seen in Figs. 1 and 3, the bottom plate I8 is forced downwardly. On moving downwardly, the bottom plate moves the guide posts to which the ram plate, upper electrode shoe and upper electrode are secured. When the upper electrode is thus moved down and two pieces to be welded between upper and lower electrodes are engagd, the pressure on the piston within the cylinder I 3 will determine the pressure exerted between the pieces engaged by the electrodes. ticular electrodes illustrated are for the purpose of welding two halves, 2I and 22 of a hollow article. Such an article is shown within the Welder in Fig. 3. It will be noted that each electrode is provided with a depression which receives one of the pieces to be welded and makes electrical The par- `secured to the frame at 28.

contact with the entire outer surface thereof exa cept in the area vof the weld.

Each guide post is provided with a fiber boot 23 that extends from the upper edge of the shoulder bushing` in the bed plate to a point be; yond the plane of the weld. When a weld is effected, a flash occurs and the boots 23 serve to protect the guide posts from the heat of the ash and metal particles that are carried by the flash. These boots may have metal facings at the point or area wherethey are struck by the ilash. The contact blades I 5 and I1 are likewise shielded from the ash by a flash shield 24 that is secured to and depends from the contact plate of the Preferably,. the rear guide posts are water cooled. To this end, each of these guide posts may be bored and a tube of lesser diameter than the bore inserted therein axially thereof so that there is an annular sDCe formed between the tube and the wall of the bore in the guide post. Water admitted through the tube will pass down the tube and up the annular space. The desirability of water cooling the rear posts is primarily because of the heating due to eddy currents induced therein by the flow of the welding current through the connectors and between the rear guide posts.

To prevent the accidental downward movement of the upper electrode, even though pressure may be applied to the upper end of the cylinder, a safety lock is provided. This safety lock includes a hook-shaped element 25 that is pivotally secured to the frame or base I on a pivot 28.y A like hook-shaped element 21 is pivotally The hook-shaped elements 28 and 21 are on opposite sides of the bottom plate I8 and include end sections 23 and 30 respectively which normally extend under the bottom plate. The elements 25 and 21 are oonnected together by a link III. At one end, this link 35 is pivoted, as at 3I, to the hook-shaped element 25, above the pivot axis 24. The other end of the link 30 is pivotally secured to the element 21 at a point 32 below the pivot axis 23. Also secured to the pivot 32 is one end of a link 33, the other end of which is secured to an operating handle or lever 34. The lower end of the operating handle is pivoted to the frame at 35. A spring 35 serves to normally maintain the handle 3C in the position in which the ends 23 and 30 of the elements 25 and 21 extend under the bottom plate Il. When the operating handle is moved against the action of the spring, to the left as yseen in Fig. 1, the hook-shaped elements 25 and 21 are swung about their pivotal connections to the frame, outwardly, to remove the end sections 28 and 30 from the path of the bottom plate I8.

Secured on the side of the machine (Fig, 4), there is a mounting panel 31 on which there are mounted two limit switches, 35 and 39. Limi-t switch 38 is provided with a pivotally mounted lever 40 which carries a cam follower 4I. A like pivotally mounted lever 42 is carried by the limit switch 39 and this lever has mounted thereon a cam follower 43. The switch lever 40 is actuated by a control cam 44 and the switch lever 42 is actuated by a control cam 45. These control cams4 are mounted upon and secured to a control rod 48 that is slidably mounted in-bearings 41 and 48 secured on the mounting panel. Extending between the cams 44 and 45 there is an adjusting screw 48. This adjusting screw is journaled in the cam 45 and secured against longitudinal movement with respect to the cam 45. On the adjusting screw, and extending through slots in the cam 45, there is a knurled wheel 58. The adjusting screw is threaded into the cam 44. Each of these cams is secured in position on the control rod by a locking screw, the locking screw 5I serving to secure the cam 44 and the locking screw 52 serving to secure the cam 45. By loosening the locking screws, one or both, and turning the knurled wheel 50. the relative position ot the cams 44 and 45 on the control rod may bead- Justed to affect the relative operation of the switches 38 and 38 with respect-to the position of the control rod.-

On the end of the control rod, there is provided a stop nut 53 which, by engagement with the bearing 48, limits the upward movement of the Y control rod. The control rod is resiliently urged A*les in an upward direction by a spring 54 that acts bracket I8 secured to the ram plate I2.

L and close adjustment may be obtained.

'Fig.'5 of the drawings,

' asaaooa Another relief valve 14 of the same kind is introdu'ced in a by-pass line 1I which by-pass line extends between thehigh/pressure line I8 and the low pressure line 83. This relief valve 1I, in the system illustrated. -is adjusted to open when the pressure in the line 85 exceeds approximately three hundred and fifty pounds per square inch.

When this valve is operating, the pressure-in the forms a clamp for the adjusting screw which'may be tightened or loosened by a bolt 59. The head of the adjusting screw is provided with graduations 80 that may be read against a mark 6| on the bracket 58. The bottom of the head of the adjusting screw 51 engages, in the downward movement of the plate I2, the operating collar 38lv to move the control rod downwardly and so eilect actuation of the limit switches 38 and 33. With the operating collar 56 a rough adjustment may be obtained for. the operationl of the limit switches with respect to the relative position of the electrodes. With the adjusting screw 51, a very fine The switches 38 and- 39 are control switches for controlling the action of the hydraulic system utilized for effectingy operation of the welder.

. 'I'he hydraulic system utilized is illustratedin This hydraulic system (Flg. 5) includes a fluid reservoir, in this instance .an'oil tank 82. To this oil tank) the inlet or low pressure side of a constant delivery pump 83 is connected by means of apipe` 8l. The outlet or pressure side `oi? the pump 63 is connected by a pipe line 65 to an-electrically operated, four-way valve 66. `One outlet of the four-way valve is connected by a pipe 61 to the lower end of the cylinder i9, another outlet from the valve86 is connected by a pipe 88 to the upper end of the cylinder i9, and a further outlet is connected by a pipe line 6,9 to the tank 62. These fourway valves are commonand well known in the art. When a solenoid 10 is energized, the valve 68 is actuated to place the lines 38 and 88 in com- `munication and to connect the linesl1 and 89.

' other. vlUponenergization o f a solenoid 1I; the

four-way valve is actuated to connect the pressure line Slto ythe line '81 and the line 88 to the low pressure line 88. With this arrangement the piston moves up in the cylinder to separate the electrodes.Y

line cannot exceed, and it is held at a pressure of three 'hundred and fifty pounds per square inch. In the line 1l, however, there is provided a. cut-oil valve 18 which, when actuated, serves to close the by-pass 1l and so nder the relief valve 14 inoperative to relieve or control the pressure in the high ypressure line 85. I'he cut-oil valve 16, is actuated through an electrically energized solenoid 11. Thus, while the valve 16 remains open the relief valve 14 operates to control the pressure in the high pressure line` 85. When, however, the valve 16 is closed, which is effected by the energization of the solenoid 11, the valve 14 becomes ineffective and the pressure inthe line 85 is controlled bythe relief valve 12 which becomes effective.

For the purpose of Aconserving power, the hydraulic system is arranged so thatdn theposition in which the electrodes are separated, only sufficient pressure is lmaintained to hold the' guide rods in their `uppermost position. To this end, there is utilized an nunloading valve 18 which serves to vent the relief valve 12 and thus effect an imbalance in this valveso that the valve re yinto the system as follows (Fig. 5): One side of the valve 18 is connected by a pipe 8| to the head or upper end of the cylinder i9. 'I'he other side of the valve is connected by a pipe 82 to one side of the pressure adjusting valve. The other side of the pressure adjusting valve is connected` by a pipe 83 to the vent of the relief valve, When the guide posts are in their uppermost position and the plate i8 has actuated the valve For the purpose of controlling the pressure acting -on the piston and in consequence the force exerted on 'pieces between the electrodes, pressure relief valves are introduced into the hydraulic system. A relatively high pressure relief valve 12 of 'the constant pressure type is'connected in the line 35 and, through a pipe 13, to the low pres` sure line 69. In the system illustrated,v this relief valve is set to maintain a' pressure in the line 63 ,of approximately one thousand pounds per lsquare inch, that' is, the valve opensthe line 83 to the low pressure line.89 above this pressure.-

This is a balanced type of relief valve of a kind well known in theart andy in which the valve is acted upon by the pressure inthe line and opens the high pressure line lto the low pressure only 18, the line 82 is connected through the valve A18, cylinder i3 and valve 66 to the low pressure line 89. Thus. oil from o-ne side of the balanced f relief valve 12 inay ilow through the pressure adjusting valve 80 and to' the low pressure line.'

their -own weight. It is 'for this reason that the valve 80 is provided. By adjusting the valve 8 8. the valve l2 may be vented'just sufficiently to maintain the desired. pressure in the lower end of the cylinder i9 so that the guide posts are maintained inv their uppermost` position. This arrangement,v while the Welder is inoperative or the electrodes separated, reducesthe load on the pump to a. minimum and so conserves power,

reduces wear on the equipment and avoids overheating of the oil.

. trolled by a relay 92.

The pressures mentioned above are for a particular welding operation and may vary in ac.- cordance with the nature of the pieces to be welded. In the hydraulic system illustrated suitable pipe lines It are utilized for carrying leakage from the various valves and instruments to the low pressure line and so to the reservoir.

In the operation, the operator presses one but; ton and the welder goes through its cycle of operation. When the head has applied pressure on the pieces between the electrodes, a pressure switch Il in combination with a time delay ini tiates the welding current. The limit switches then control the application of higher pressure and the termination of the welding current. The termination of the welding current initiates a time delay which after the lapse of a predetermined time causes the head to lift. At the top of the stroke, the pump unloads and everything l is reset for another cycle. This automatic control is illustrated diagrammatically in Fig. 6.

Current for the system is taken from a 110/220 volt. alternating current supply, represented by the line wires Il and 8l and theneutral Il. The solenoids 10 and 1I for operating the four-way valve II, the solenoid 11 for actuating the valve 1l, a circuit breaker 9| for controlling the current to the primary of the transformer 3, and the primary of the transformer I are, when in circuit, connected across the line wires Il and il. The remaining elements in the system are connected, when in circuit, between the line wire 'Il and the neutral n.

In the system illustrated, the solenoid Il for effecting operation of the four-way valve ,ln a manner to connect the lower end of the cylinder to low pressure and the head end to the pressure side, and so effect forward movement of the electrode shoe Il, is connected across` the line through normally open contacts ila and 02h con- The solenoid Il through which reverse movement of the electrode shoe Il, movement away from the electro4 shoe l, is effected is connected across the line through the normally open contacts lla and ub of a relay In like manner, the solenoid l1 of valve Il is connected across the line through the normally open contacts a and b of a relay Il; the circuit breaker Il is connected across the line through normally open contacts lla and Ib of a relay e5; and the primary of the transformer I is connected across the line through the normally open contacts lla and IIb of the circuit breaker ll.

To start the forward or downward movement of the electrode shoe, the relay I! is energized to effect closing of the contacts 02a and IIb. This is effected through a normally open push button switch 90 having contacts "a, b and "c that are bridged when the push button is pressed to close the switch. When this occurs. relay l2 is connected across wires Il and Il as follows, a wire l1 connected to wire Il, a normally closed push button switch el, normally closed contacts c and "d of relay il, relay l2, a wire Il, contacts .ela and c of switch I. and a wire lll to the neutral el. When the relay l! is thus energized,

' contacts "a and .2b are closed.v Also contacts .2c and .92d of relay I2; are closed. Upon Vclosing. these latter contacts complete a hold-in circuit for the relay I Lwbypassing the switch Il, as follows: wire Il, a wire lll, contacts lic and ltd, and a wire' Il! to the neutral Il.

In addition toeffecting the energization of relesntheclosingoftheswitch Iletl'ectsthe energization of a relay III and a time delay relay Ill. The circuit to the relay III is through the normally closed, relay contacts c and d of relay 93, a wire III, relay III, a wire l" connected between relay I" and contact "b of switch contact c and wire III to wire Il. The time delay relay IM is connected across the wires |05 and l" in parallel with the relay Ill and is so energized upon energizatlon of relay I.

Upon energization, relay Ill closes its normally i open contacts Ila and Illlb and so completes a hold-in circuit, bypassing'the switch Il, for itself and the time delay relay IM. This circuit includes the wire l", contacts Illia and lub, a wire IIII, a wire |08, a normally closed push button stop switch lle, a wire Ill, lnormally closed limit switch contacts 38a and IIb of switch Il, and a wire Il I to the neutral Il. After a time delay, for which the time delay relay I 1s set. this relay closes its normally open contacts Illa and IMb. f

By the foregoing action, the electode shoe Il has been brought down and exerts pressure upon the pieces placed between the electrodes. When this pressure reaches a predetermined value, the pressure switch 89 is actuated and closes its contacts 89a and ub. When both the time delay relay contacts IMa and Illb and the pressure switch. contacts "a, leb are closed, a circuit is completed t0 the 'circuit breaker relay l! as follows: line wire 8l, a wire H2, relay e5, a wire III, contacts lMa, 1Mb', a wire lil, contacts "a, "b, and a wire lil to line-connected wire III. The circuit breaker relay thus connected in circuit closes its normally open contacts a, 5b and so effects the energization of the circuit breaker Il. In addition the normally open contacts "c and d of )relay 95 are closed and complete a hold-in circuit, bypassing the pressure switch and time delay relay contacts. The circuit breaker contacts lla, Ib are thus closed and the primary of the transformer I is connected across the line ll-ls. Current is thus induced in the secondary and flows through the pieces between the electrodes. This is a heavy current and the pieces become heated in the weld area. The metal becomes plastic and the electrode shoe I4 moves closer to the electrode shoe l under the pressure applied. This movement effects the actuation'of the limit switches, first the limit switch Il and then the limit switch il.

When the switch I! is actuated, its normally open contacts Ila, lsb are closed. Upon closing, the high pressure relay el is energized through the following circuit: line .wire' Il, a wire III,`relay N, a wire H1, contacts "a, IIb anda wire lll to neutral 0l. Contacts 94a, Mb of relay Il are thus closed and the solenoid 11 of valve 10 is energized. 'The valve 1l closes and 'renders the pressure relief valve 'I4 inoperative.

The pressure in thel system and acting on the piston in the' cylinder Il is thus controlled by upward movement of the electrode shoe Il. This action is effected, upon the actuation of switch il by separating the normally closed contacts "a and b thereof and closingl the normally open contacts c and Ildthereof. Upon opening,

the contacts llc, b break the circuit to the relay contacts 86d, ne.

are also useful forset up and trial purposes.

cuit to the primary of the transformer I is broken at the contacts Ila. lib. I ,Y

f When the contacts llc and 32d close, the circuit initiated tothe time delay relay III is as follows: line wire Il, tvire ||l,'a wire |20. a wire |2I, relay Ill, a wire |22. contacts 22o. 22d, and a wire |28 to the neutral l0; Relay H9, after r the time delay for which it is set. a time sufilcient to complete the weld and start the cooling of the metal, closes its normally open contacts Illa. Illb. This completes a circuit through the re` verse relay "as follows: line wire 28. wires lli, ||2|. contacts Illa, Iltb. a wire |24, relay l2. a wire '|2l. normally closed contacts of the push button switch I.. and a wire |28 to the neutral Il.

Upon the opening of the contacts 38a and lib,

` the circuit te the relays in; and m wesbroken. r Upon energization of lrelay 02, the circuitl to the handle to the left (Pig. 1) which releases safety-lock. yAt the same time, he presses the pusnbutton u. Upon pressing the push button f It, relay 92 is energized andf'closes the circuit Vto the solenoid 14|. The valve it is thus actuated to interconnect the cylinder 20 with the -high pressure and lowl pressure lines such that the piston' moves down in the cylinder.- 'lhe vupper electrode is thus brought down, receives the upper of the pieces. the piece 2|, and presses the pieces together in the edge to edge relation. The guide pins enter complementary openings in the uppe electrode and position the electrodes as they approach each other. Y

relay .92 is broken at the contacts llc, 93d of l relay. De-energization of relay 92 breaks the circuit yto the forward solenoid 10 at the contacts 22a, 02h. Also energization of relay 92, closes the circuit to the reverse solenoid 1| of the fourway valve 88. Thus, the valve is actuated to conneet the lower end or the cylinder is wine nigh pressure line, and the upper end of the cylinder to the low pressure or exhaust. The piston thus moves upwardly, moving the electrode shoe 'il away from the electrode shoel. Also, as the ram plate moves upwardly the switches 2s and II `are released and resume their normal positions.

When the ram plate reaches its, uppermost posltion. the unloading valve 18 is actuated and the i system is in its initial relation and ready. Upon the pressing of the push button switches, the

circuit to the reverse vrelay 93 is broken at the As the time delay relay |l0 is now deenergized,.through the reopenlngof contacts llc, d of switch, the relay' 03 re' mains de-energized until again energized in the cycle of operation. The push button switch l is provided with normally open contacts lla, "b, through which a circuit may be 'completed'to the reverse relay 93 so that at any time during the cycle of operation, the electrode I4 may be'raised.- When the switch Il is actuated, theforward action in the cycle is arrested ,by the breaking of the control circuit at the normally closed contacts 98e, Qld and a circuit is completed to the -reverse relay When the electrodes are inl engagement with the `pieces and exert a predetermined pressure thereon, and the time delayrelay, IM has operated. the primary of the transformer 2 is connected across the line 82-89. As the upper elecltrode moves down, the contact blades Il and I1 are engaged. A circuit is therefore completed from one side of the transformer secondary,

lower electrode shoe 8./lower electrode '|piece 22, piece 2 i, upper electrode Il, upper electrode shoe lli/#and contact blades I8 and l1 to the other side of the secondary of the transformer. 'nie welding current thus ilows Ithrough the pieces 2| and 22 in the area/ at which the weld is to be' effected.

During the foregoing operations, the-shut-oi! valve 16 is open. In consequence, the relief valve 14 determines thepressure in the high pressure line 6l and the force or pressure exerted on the pieces between the electrodes. This condition maintains while the pieces are being heated in the weld y/area and until the metal thereof-becomes sufllciently plastic so that under thev pres.- sure exerted on the pieces,'the metal flows.`

As the top plate moved down, the head of the adjusting screw I1 engaged the operating collar 56 and the controlV rod was moved slightly but insufficiently, though nearly so, to actuate the switch 49. When the metal of the pieces is heatof the pieces, the switch 2l is actuated. The shut-'on valve .18 is instantaneously closed and the high pressure acts on the piston in the cylinder 20. Under this higlupressure the metal of each piece is caused to flow into fthe other, the two pieces being quickly moved together until-the upper electrode is stopped by the'upper electrode as follows: wire ll, alwire|21. contacts Ila. 88h

of switch It, reverse relay 82, wire |25. normally l closed contacts "d, c of switch li and wire |26 toneutral 90. Whenever the relay" 92 is energized, the hold-in circuit tor the relay'is broken at the contacts e and uf of relay 92. Sini-v ,f larly. the welding current may be cui: of! at any time by `the actuation of the push button switch |00. Another push button |21' is provided by means of which the welding' current may be in itiated independentlygpf the time delay relay |04. This switch lain a circuit 'parallelwith the con-'- tacts Illa, lub of the relay |04 and when closed bypasses these contacts. These manual controls L .The operation of the welder is :is follows: The

operator places the pieces, such as the pieces 2| f and 22 (Fig. 3) in the lower electrode with' the edges at which the pieces are .to be welded in contact.l He then moves` the safety-lock operating shoe engaging the sizing blocks lo,

Immediately following the application vof high pressure, the cam u actuates the switch Il.

This opens the circuit to the relay and def energizes the relay. As a consequence. the circuit breaker 9| isde-energized, the welding current cut of! and the time delay relay Il! is energized.

The weld is completed and as the metal begins to cool the time delay relay operates. By this action thel solenoid 10 is de-energized and the solenoid 1| energized. The valve I8 is thus actuated to raise the piston in the cylinder and sor tinuous operation. Theoperating mechanism is comparatively simple and the pressure on the pieces being welded may be accurately controlled in relation to relative position oi the electrodes and the progress of the weld. As arranged and constructed the electrodes are accurately positioned in all relative positlonsand the pressure exerted on the pieces to be welded ls uniformly distributed.

It will be obvious that various changes may be made by those skilled in the art in the embodiment of the invention illustrated in the drawings and described in detail above within the principle and scope of the invention as expressed in the appended claims.

I claim: i

1. An electric welder of the type described comprising in combinationa base, iour posts slidably mounted in and extending from the base, an electrode shoe supported on the base among said posts, a platesecured to theends of said posts extending from the base, an electrode shoe mounted on the plate among the posts, another plate secured to the other ends of said posts. and means for acting on said latter plate to effect movement of the posts in two directions and throughout their limit of movement.

2. An `electr1c welder of the type described comprising in combination a base, four posts slidably mounted in and extending from the base, an electrode shoe supportedon the base among said posts, a plate secured to the ends of said posts extending from the base, an electrode shoe mounted on the platelamong the posts, another plate secured to the other ends of said posts, and hydraulically actuated means for acting on said latter plate to eiiect movement thereof toward and away from the base.

3. An electric Welder of the type described comprising in combination two relatively movable electrode supports, pressure actuated means for effecting relative movement oi.' the supports toward and away from each other, means for applying pressure of one value to said pressure actuated means to effect movement of the electrode supports toward each other and for eecting a pressure engagement of pieces betweenK electrodes carried by the electrode supports. means for supplying welding current and control means therefor including a pressure actuated switch and a time delay switch arranged to coniointly control the'start of the ilow oi welding current, additional means for cutting oi! the welding current, and means operative immediately upon the take-up as the weld is being effected for increasing the pressure applied to said pressure actuated means.

4. An electric welder of the type described comprising in combination two relatively movable electrode supports, pressure actuated means for effecting relative movement of the supports toward and awayfrom each other, means for applying pressure of one value to said pressure actuated means to eiIect movement of the electrode supports toward each other and for eilecting a pressure engagement of pieces between ele( trodes carried by the electrode supports, means for supplying welding current, means .operative upon slight relative movement oi' the electrodo supports on the take-up as theweld is being effected for increasing the pressure applied to said pressure actuated means, additional means operative upon slight additional relative movement of the electrode supports for cutting oi! the welding current, and common actuating means therefor, and means for effecting reverse movement of the electrode supports after a predetermined time delay following the cutting oi! of the welding current.

5. An electric welder o! the type described coin- -prising in combination a base arranged to support an electrode. posts extending from and slidably mounted in said base, a plate secured to the ends oi the posts above the base and arranged to support another electrode. another plate secured to the posts below the base. and pressure actuated means below the base connected to said last mentioned plate for eiiecting movement of the electrode carried by said first mentioned plate both toward and away from the base.

6. An electric welder oi the type described comprising in combination a base, arranged to support an electrode, posts extending from and slidably mounted in said base, a plate secured to the ends of the posts above the base and arranged to support another electrode, another plate secured to the posts below the base. a cylinder below the base and mounted thereon substantially centrally o! said last mentioned plate, a piston within the cylinder and a piston rod extending irom the piston and connected to the plate for eiiecting` movement of the electrode carried by said nrst mentioned plate toward and away from the base.,

7. An electricwelder of the type described comprising in combination a base arranged to support an electrode, posts extending from and slidably mounted in said base, a plate securedi to the ends of the post above the base and arranged to support another electrode, another plate secured to the posts below the base, pressure actuated means below the base connected to said second mentioned plate for moving the first mentioned plate towards the base, restraining means normally positioned below said second mentioned rectly thereon for releasing said restrainingmeans.

Y 8; An electric Welder of the type described comprising in combination two relatively movable electrode shoes, means for eiiecting relative movement oi the electrode shoes, means for supplying electric current to electrodes carried by the electrode shoes, and control means including means for actuating said electrode shoemoving means for effecting movement of the electrode shoes toward each other, means operated in accordance with the relative position of the electrode shoes for cutting otl' the current to the electrode shoes and means operated concomitantly with the cutting of! of the 'current to the electrode shoes for initiating reverse relative movement of the electrode shoes including means for delaying the reverse moment of the electrode shoes i'or a predetermined time interval.

9. An electric welder ot the type described comprising in combination two relatively movable electrode shoes, means i'or eiiecting movement oi the electrode shoes. means for supplying electric current to electrodes carried by the electrode shoes, and means for automatically controlling trode shoe moving means to effect relative movement of the electrode shoes away from each other.

v10. An electric welder `oi the type described comprising in combination two relatively movable electrode supports, hydraulically actuated means for effecting relative movement of the electrode supports toward and away from each other, a pump for supplying fluid under pressure for said hydraulically actuated means, means for controlling the pressure supplied by the pump including constant pressure relief valves and a cut-ofi' valve for one of said constant pressure relief valves and control means for said cut oi! valve including means operative upon movement oi' the electrode support on the takemup as a weld is effected.

11. An electric welder oi' the type described comprising in combination a bed plate, a ram plate movable towardy and away from the bed plate, pressure actuated means for4 moving the ram plate,.means for applying a pressure oi'vone value to said pressure actuated means to eil'ect movement of the ram plate towards the bed plate, means operative for increasing the pressure applied to said pressure actuated means, and control means therefor including means acted ,upon directly by the ram plate.

, 12. An electric Welder oi' the' type described comprising in combination two relatively movable electrode supports, means for eitecting relative movement oi' the electrode supports toward and away from each other. control means, and an actuating element for said control means positioned electrode supports.

13. An electric welder of the type described comprising in combination two relatively movable electrode supports, electrodes carried by the supports, means for effecting movement of the electrode supports, means for supplying electric current to the electrodes, means for automatically controlling the operation of the welder including means for effecting actuation of said electrode support moving means to effect relative movement oi the electrode supports toward each other, and means operated in accordance with the relative position of the electrode supports for cutting ofi the current supplied thereto including a control element and actuating means therefor positioned to be engaged by one of said relatively movable electrode supports.

l 14. An electric Welder of the type described comprising in combination two relatively movable electrode supports, electrodes carried by the sup'- ports, pressure actuated means for effecting relative movement of the electrode supports, means for supplying electric current to the electrodes. means for automatically controlling the operation of the Welder including means for effecting actuation oi' said electrode support moving means to efl'ect relativemovement of the electrode supports toward each other, means for cutting of! the .current supply to the electrodes, means for aiecting said pressure actuated means and con- $0tro1 means for-said last two mentioned means positioned to be engaged by an electrode support.

GEORGE J. FRISCHMANN. CARL 1". BRU'NNER. 

